Railway braking apparatus

ABSTRACT

Apparatus for indicating the condition of hand brakes on railway cars and for applying and releasing railway car parking or hand brakes automatically in response to predetermined conditions including movement of a train, wayside conditioning apparatus, wayside operating mechanism, a signal controlled by an operator and performance of predetermined railway operating procedures, such as completion of an air brake test procedure. The apparatus may respond to mechanical, electrical and electronic signals and may operate on pneumatic or electric power provided from the service air brake system of a train or from a source of power outside of such air brake system. A brake system for a railway train equipped with brakes is disclosed comprising a first device for applying such brakes to inhibit movement of the railway train, a second device operable under certain predetermined conditions to cause the first device to apply such brakes, a third device normally in a first condition but responsive to the application of such brakes by operation of such second device to assume a second condition, and a fourth device effective when the third device is in its second condition to provide an indication thereof.

This application is a Divisional Application of application Ser. No.08/278,937, filed Jul. 22, 1994.

FIELD OF THE INVENTION

The present invention relates, in general, to braking apparatus forrailway cars and, more specifically, this invention relates to apparatusfor indicating the condition of hand brakes and for applying andreleasing railway car parking or hand brakes, particularly includingapparatus for performing such functions automatically in response topredetermined conditions.

BACKGROUND OF THE INVENTION

Usually when railway cars are taken out of a train and parked at asiding or yard, the hand brakes on at least some of the cars are appliedas a precaution against unwanted or unexpected movement of the cars. Atypical hand brake may consist of apparatus for manually applying abrake shoe or shoes to one or more wheels of a railway car by turning ahandwheel or pumping a handle connected by gears and/or linkages to thebrake shoe engaging mechanism and a mechanism for releasing the handbrake and causing the brake shoe or shoes to be disengaged from contactwith the wheels.

A typical railway car hand brake can be released turning the handwheelor pivoting a release lever. Pivoting the release lever will cause fullrelease of the hand brake preferably without spinning the handwheel ormoving the handle used to apply the brakes. This type of system issometime referred to as a "quick release" hand brake. Prior to thepresent invention, the hand brakes were manually released separately oneach car or on each end of a car equipped with hand brakes at each endand it is possible that the hand brakes may not all have been releasedwhen a train or group of cars is moved. When this occurs one or more ofseveral serious problems can result. Among them are worn brake shoes,brake heads and wheel treads, cracked or broken wheels from overheating,worn rail heads, impaired truck action and damage to trucks. All ofthese conditions are detrimental and costly because they waste power andcause damage to trains and lading.

It is desirable to avoid these undesirable conditions and unnecessaryexpense by providing apparatus to reduce or eliminate unreleased handbrakes or parking brakes. The terms "parking brake" or "hand brakes" asused herein are intended to include not only the conventional handbrakes described above which are usually applied and released manuallyby a member of the train crew but also brakes which can be applied orreleased from a remote or central control point such as the locomotiveor caboose and which may utilize vacuum, air pressure, electricity orother source of power to activate or release a brake on a standingrailway car in a yard or siding. Such hand brakes or parking brakes mayinclude portions of the service brake system. As used herein, the term"service brakes" or "service air brakes" is intended to refer to airbrakes usually on a train and controlled from a central location,usually the locomotive of a train, to retard the movement of a train orgroup of cars connected to a locomotive.

The objectives of this invention are to provide one or more of thefollowing means of avoiding movement of a train with the hand brakes orparking brakes in an applied condition: signalling such condition,providing remote or central control apparatus for applying or releasingparking brakes on a train, and providing apparatus for automaticallyreleasing parking brakes on a train in response to predeterminedconditions with or without intervention of a member of a train crew.

Because of the strict operating and safety rules applicable to trainoperation in the United States and other countries the above objectivesmust be accomplished without interfering with proper train equipment andoperation as required by practices established by the Association ofAmerican Railroads and by cognizant government agencies. These practicesusually require performance of an air brake test procedure before atrain is moved out of a yard or terminal.

SUMMARY OF THE INVENTION

In a first aspect of the invention there is disclosed apparatus foreffecting a change in the condition of a hand brake system on a railwaycar equipped with a hand brake system and a service brake system inresponse to at least one of a predetermined group of response triggeringconditions including movement of such railway car, speed of suchmovement, the application of service air brakes, the release of serviceair brakes, the applied condition of such hand brake, the releasedcondition of such hand brake, the level of air pressure in such airbrake system and a signal from a device controlled by a human operator,such apparatus including a first device for detecting at least one ofsuch response triggering conditions and a second device, operativelyassociated with the first device, for producing a predetermined signalindicating that such condition has been detected.

In a second aspect of the invention there is disclosed a railway brakesystem for a railway train comprising a locomotive and at least one carequipped with brakes, the brake system comprising a first apparatus forapplying such brakes to inhibit movement of the railway train, a secondapparatus operable under certain predetermined conditions to cause thefirst apparatus to apply such brakes, a third apparatus normally in afirst condition but responsive to the application of such brakes byoperation of the second apparatus to assume a second condition and afourth apparatus effective when the third apparatus is in its secondcondition to provide an indication thereof.

In a further aspect of the invention there is disclosed a railwayparking brake system comprising a first device for applying a parkingbrake, a Second device for releasing such parking brake, a third devicefor selectively conditioning said second device to an operative or aninoperative condition and a fourth device for applying a parking brakereleasing force to the second device.

In another aspect of the invention there is disclosed a railway parkingbrake release system for a railway train consisting of at least one carequipped with fluid pressure operated service brakes and an auxiliaryparking brake apparatus and having mechanisms for actuating suchauxiliary parking brake apparatus to a braking condition and forreleasing such auxiliary parking brake apparatus, the release systemcomprising an inlet connectable to the fluid pressure for such servicebrakes, a fluid pressure responsive first device in communication withsuch inlet and responsive to predetermined levels of fluid pressuretherein to be conditioned to an operative or an inoperative conditionand a parking brake release second device controlled by the first deviceand operable from a first position when the first device is in aninoperative condition in which such auxiliary parking brake apparatusmay be actuated to a braking position and operable to a second positionwhen the first device is in an operative condition in which theauxiliary parking brake apparatus will be released upon operation of thesecond device.

In a fifth aspect of the invention there is provided a brake system fora railway train consisting of at least one car equipped with fluidpressure operated service brakes, the brake system comprising anauxiliary parking brake apparatus operable by fluid pressure, a sourceof fluid pressure for the auxiliary parking brake apparatus, a firstmechanism for connecting the source of fluid pressure for the auxiliaryparking brake apparatus to the auxiliary parking brake apparatus, asecond mechanism for operating the auxiliary parking brake to a brakingposition, a third mechanism responsive to a predetermined level of fluidpressure for releasing the auxiliary parking brake and a parking brakerelease control for controlling the application of fluid pressure to thethird mechanism to thereby control the release of the auxiliary parkingbrake apparatus.

A sixth aspect of the invention provides a railway hand brake releasesystem for a manually applied hand brake equipped with a quick releasemechanism, the release system comprising an electrically operatedsolenoid valve, a first device for controlling the supply of electricpower to the solenoid valve, a fluid pressure responsive device foractuating the quick release mechanism to release the hand brake and acontrol arrangement including the solenoid valve for controlling theapplication of fluid pressure to the fluid pressure responsive device tocause the release of the hand brake.

OBJECTS OF TEE INVENTION

Therefore, it is a primary object of this invention to provide apparatusfor indicating a "hand brake applied" condition on a railway car and forreleasing an applied hand brake which apparatus will function reliablywithout deviating from or requiring changes to current railway operatingprocedures.

Another object of this invention is to provide such apparatus which willoperate automatically in response to performance of an air brake testprior to in-train operation of a railway car.

It is another object of this invention to provide such apparatus whichwill not interfere with manual application and release of hand brakes.

Still another object of this invention is to provide such apparatuswhich is power operated.

It is also an object of this invention to provide hand brake releaseapparatus which is operated by air pressure in the air brake system ofthe train.

Another object of this invention is to provide a hand brake releasesystem which utilizes an air pressure distribution system separate fromthe air pressure distribution system for the service air brakes.

A further object of this invention is to provide hand brake releaseapparatus which is controlled by electrically or electronically operatedequipment.

Yet another object of this invention is to provide a hand brake releasemechanism operated by a source of power independent from the airpressure in the air brake system.

A still further object of this invention is to provide a hand brakerelease system operated by a source of electric power.

These and various other objects and advantages of the present inventionwill become apparent to persons skilled in the railway braking art fromthe following more detailed description of the invention, particularlywhen such description is taken in conjunction with the attached drawingsand the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic illustration of one form of the invention whichutilizes a motion sensor;

FIG. 2 is a partial schematic illustration of the form of the inventionshown in FIG. 1 but modified by the use of an electrically poweredrelease actuator;

FIG. 3 is a schematic illustration of an alternative form of theinvention which includes a transducer pressure switch;

FIG. 4 is a schematic illustration of another alternative form of theinvention in which the parking brake system is separate from the servicebrake system;

FIG. 5 shows a system similar to that depicted in FIG. 4 but which doesnot require a separate air distribution system for the parking brakes;

FIG. 7 shows the system of FIG. 5 modified to utilize electricallyoperated elements;

FIG. 8 shows another form of the invention which can be readilyretrofitted to existing railway stock;

FIG. 9 shows a system similar to that shown in FIG. 7, modified toutilize electrically operated elements;

FIG. 9 shows a modified version of the form of the invention depicted inFIG. 4;

FIG. 10 shows a form of the invention particularly useful with truckmounted brakes and retaining a conventional hand brake actuator;

FIG. 11 shows another form of the invention in which operation of therelease lever of a hand brake actuator is electrically controlled;

FIG. 12 shows a form of the invention employing an air operated releasecylinder for a hand brake actuator;

FIG. 13 depicts a hand brake release system of the invention in whichoperation of a release cylinder is controlled by air pressure in a handbrake air distribution system which is separate from the service brakeair distribution system;

FIG. 14 shows a modified version of the form of the invention of FIG.13;

FIG. 15 pictures a form of the invention which provides a visualindication of hand brake condition;

FIG. 16 is a form of the invention in which a visual signal of handbrake condition is operated by air pressure;

FIG. 17 illustrates another form of the invention which provides avisual signal indication of hand brake condition;

FIG. 18 illustrates another version of the form of the invention shownin FIG. 15;

FIG. 19 is a side elevation view of a pulley which can be used in theform of the invention shown in FIG. 15;

FIG. 20 shows a modification of the invention as pictured in FIG. 16using double acting cylinders to operate visual signals;

FIGS. 21 through 24 comprise a schematic representation of a form of theinvention, which includes a release ensuring feature, in various stagesof operation;

FIG. 25 is a schematic representation of a simplified version of theform of the invention shown in FIGS. 21 through 24;

FIG. 26 is a schematic block diagram of the parts and piping for anautomatic form of the invention;

FIG. 27 is a schematic illustration of a hand brake release valve ofFIG. 26 and its associated T-valve with the service air brake systemshut off;

FIG. 28 is a view similar to FIG. 27 but with the service air brakesystem connected and the air brakes not applied;

FIG. 29 is a schematic view of the hand brake release valve of FIG. 27with the service air brakes applied;

FIGS. 30 through 32 are schematic views of a valve used in a form of theinvention which operates automatically to release hand brakes when anair brake terminal test is performed showing the valve in various stagesof operation;

FIG. 33 is a schematic view of the control valve used in the form of theinvention in FIG. 26 with the control valve shown in its open or normalposition;

FIG. 34 is a schematic view of the control valve of FIG. 33 with thecontrol valve shown in its exhaust position; and

FIG. 35 is a schematic view of the control valve of FIG. 33 with thecontrol valve shown in its closed position.

DESCRIPTION OF THE INVENTION

Prior to proceeding to a more detailed description of the presentinvention, it should be noted that for the sake of clarity, identicalcomponents having identical functions have been designated by identicalreference numerals throughout the drawings.

In conjunction with the description of some of the hand brake controlmechanisms of this invention it would be helpful to understand certainrailroad operating procedures relating to air brakes and hand brakes.One of these procedures previously referred to herein is the air braketest procedure which must be performed before a freight train which hasbeen made up or whose consist has been changed can be moved out of ayard or terminal. A typical air brake test procedure may requireperformance of the ten steps hereinafter described after the cars havebeen connected to a locomotive or set of locomotives.

(1) Hand brakes or parking brakes are engaged.

(2) Air brake hoses for the service air brakes are connected.

(3) The air brake system including pipes and reservoirs is charged to apredetermined pressure level.

(4) Air pressure leakage is checked to ensure that it does not exceed apredetermined maximum level, e.g. five pounds per square inch per minutein the air brake pipe.

(5) Air brakes are applied to a "normal" level by operating the maincontrol valve in the locomotive to reduce air pressure in the air brakepipe by a predetermined level, e.g. 10 pounds per square inch. Thiscauses the application of the air brakes on each car by the air pressurein the reservoirs on each car which will supply air to the brakecylinders under control of the railway car air brake control valve. Atypical air brake system may include an auxiliary and emergencyreservoirs.

(6) A brakeman walks along the train and checks that the service brakeson all cars have operated and brake shoes have been engaged.

(7) A full application of service air brakes is made by further reducingpressure in the air brake pipe to a predetermined level, e.g. 20-25pounds per square inch.

(8) Service air brakes are released by manipulating the control valve inthe locomotive.

(9) The air brake system is again charged to proper level.

(10) Hand brakes or parking brakes are released.

Referring now to FIG. 1, there is shown a block diagram of one presentlypreferred form of the invention in which an electronic or electricalsignal generated by a motion sensor is used to control operation of ahand brake or parking brake. The motion sensor 10 can be an infrared orother light sensitive motion sensor, certain types of which are known tothose skilled in the art. The motion sensor 10 can be mounted on arailway car, not shown, to sense relative motion between the car and theground, rail or ties. When the relative motion between the car and thereference exceeds a predetermined speed, an electrical signal will betransmitted over an electrical conductor 12 to a control box 14. Thetrain speed at which this occurs should be sufficiently high to avoidgenerating a signal when a car is bumped or otherwise inadvertentlymoved but not so high as to allow appreciable dragging of a car withlocked brakes. A preferred embodiment of the invention would cause asignal to be transmitted to the control box 14 at car speeds of about 10miles per hour or higher. The motion sensor 10 may be adjustable toallow selection of a speed range to suit conditions or the desires of aparticular train operator. Signal input to the control box 14 from themotion sensor 10 may be used directly or after amplification or tooperate a relay, not shown, ultimately to control the application ofpower from a battery 16 or other source of electrical power to a magnetvalve 18 which is actuated to allow air in service brake air pipe 20 tobe applied to hand brake release cylinder 22. This causes piston rod 24to move in a predetermined direction to move hand brake release lever 26to a brake releasing position. Hand brake release lever 26 is part of ahand brake or parking brake actuator mechanism 28 which has a handwheel29. Prefersbly, parking brake actuator mechanism 28 is of the quickrelease type.

Alternatively, as seen in FIG. 2, a solenoid 30 may be substituted forthe magnet valve 18. In such case the link or piston rod 32 of thesolenoid 30 can be directly connected to brake release lever 26 and willeffect release of the hand brake.

A solar charger 34 (FIG. 1) of any commercially available type andcompatible with the battery 16 may be included in the system to keepbattery 16 sufficiently charged to operate as described above. This isparticularly important when the brake release lever 26 is operateddirectly by a solenoid 30 powered by the battery 16 as shown in FIG. 2.

To prevent continual operation of the release system while a train ismoving, a switch 36 may be provided on the hand brake actuator 28.Switch 36 will be open and prevent the flow of current from battery 16to magnet valve 18 or solenoid 30 unless the hand brake or parking brakeis on. It will be possible for those skilled in the art to devisevarious alternative physical arrangements of switch 36, the circuitry ofcontrol box 14 and the mechanism of hand brake actuator 28 to accomplishthe desired result of making the system operative only when the handbrake or parking brake is applied, the car is moving and the air brakebrake pipe is in a charged condition.

As will be understood by those skilled in the art, the brake releasesystem described above can be installed on a railway car withoutaffecting the air brake system or the service or parking brakes on anyother car and will operate effectively on any car in a train on which itis installed irrespective of whether of not an identical release systemor any other hand brake release system is installed on any other car inthe train. Thus it may be retrofitted on a single car or any givenportion of the cars in a train at the option of the car owner. Nomodification is required to the air brake system controls on thelocomotive nor is normal manual hand brake application and releaseaffected in any way. It is desirable, as previously stated, thatoperation of the hand brake release system be limited to those timeswhen the air brake air pipe is fully charged, indicating a normal airbrake system condition without the air brakes being applied. FIGS. 2 and3 show such a system in which a transducer or pressure switch 36 isprovided and is introduced into the circuitry of the control box 14 in amanner readily understood by those skilled in the art which will notpermit operation of the hand brake release system unless the air brakepipe is charged to a predetermined level in accordance with railwayoperating and safety rules.

The hand brake release system shown in FIG. 4 utilizes a hand brake orparking brake application and release system which is separate from theservice brake system making it possible to eliminate the presently usedtype of hand brake actuator employing handles, wheels or levers, chains,chain drums and release mechanisms. Instead the system consists of ahand brake air pipe 38 separate from service air brake air pipe 20, aparking brake cylinder 42, a spring operated set of brake shoes 44 and abrake pressure spring 46.

It should be understood that the brake shoes and rigging can be the sameones used as the service brake and that in such event it is onlynecessary to add a parking brake cylinder 42 as an auxiliary means ofengaging the brake shoes 44. It should further be understood that thebrake shoe arrangement shown is for purposes of illustration only andthat various brake arrangements may be utilized, including but notlimited to clasp brakes and disc brakes as would be recognized by thoseskilled in the art.

This form of parking brake is particularly suited for use on carsmounted on trucks having at least two axles so that a single parkingbrake cylinder 42 can be used to control a pair of opposed brake shoes44 which engage one wheel on each of the two axles. Of course, more thanone parking brake cylinder 42 and more than a pair of brake shoes 44 maybe employed.

Operation of the system shown in FIG. 4 is described below.

With the hand brake air pipe 38 in charged condition compressed airenters chamber 48 of parking brake cylinder 42, compressing brake spring46 and holding brake shoes 44 in released position out of contact withthe wheels of a railway car truck, not shown. To apply the parkingbrakes, the engineer exhausts air in the hand brake air pipe 38, causingthe pressure to drop in the chamber 48 and the brake shoes 44 to bepushed into braking position by brake spring 46. This condition will bemaintained until the engineer determines that the parking brake shouldbe released which he accomplishes by directing air from a source ofcompressed air, which may be the locomotive air brake compressor, notshown, into the hand brake air pipe 38 and via the air pipe 38 into eachparking brake cylinder 42, releasing all of the parking brakes 44 in thesystem.

This puts complete control of both the application and release of handbrakes in the engineer, reducing the likelihood of improper or spurioushand brake operation. It can be seen that in the event of accidental orother unforeseen separation of a train into two or more parts, oftenreferred to as a "break-in-two", a condition which will usually cause anemergency application of the train's service air brakes, the parkingbrake air pipe 38 would probably also be severed and the parking brakes44 will be applied under conditions not being controlled by theengineer. This might result in a sudden severe application of brakingforce to the separated portions of the train which could in turn causedamage to the train or its lading. If desired, a choke valve or othercontrol 39 can be interposed in the pipe line between the hand brake airpipe 38 and the parking brake cylinder 42 which would be effective underconditions of sudden drop in pressure in air pipe 38 to restrict orchoke the flow of air out of chamber 48. This would ensure that in thespecial situations described above the parking brake would be appliedonly after train speed is substantially reduced, thereby avoiding theharmful results of a sudden severe application of both service brakesand parking brakes simultaneously.

There is shown in FIG. 5 a modification of the system described inconnection with FIG. 4 but which does not require a separate parkingbrake air pipe. Instead brake pipe 20 is connected by pipe 50 through atiming valve 52 to parking brake cylinder 42. Timing valve 52 maypreferably be constructed to allow unrestricted flow of air to theparking brake cylinder 42 but to limit air flow out of it. It will beseen by those skilled in the art that after brake pipe 20 is chargedwith compressed air, spring 46 will be compressed by air pressureadmitted by timing Valve 52 which allows the full flow of pressurizedair into chamber 48. The escape of air from chamber 48 is howevercontrolled by timing valve 52 so that the application of the parkingbrake is delayed from the time that a reduction in brake pipe pressureoccurs. If desired, the length of the delay produced by thing valve 52can be adjustable. The flow of pressurized air into the parking brakecylinder 42 can also be delayed and the delay in transmitting areduction in brake pipe pressure through timing valve 52 can bedifferent from the delay required to transmit an increase in suchpressure by apparatus known to these skilled in the art.

The delay in releasing the parking brake, if employed, can be made toensure that such release does not occur while the service brakes areengaged and the delay in applying the parking brake helps avoid thedetrimental braking conditions which may occur upon simultaneous suddenapplication of beth service and parking brakes during an emergencysituation such as break-in-two.

There is shown in FIG. 6 a modified version of the system shown in FIG.5. In the modified version the timing valve 52 is replaced by anelectrically or electronically operated valve 56. The valve 56 may beconnected by an electrical conductor 54 to a switch or other control 58operated by the engineer which control 58 controls the application ofpower to the operating means for valve 56. Instead of an electricalconductor, 54 the valve 56 may include a radio or infrared receiverand,associated devices so that the valve 56 may be operated by a radiocontrol or infrared transmitter 60 in a manner known to those skilled inthe art. The radio control 60 can be located in the locomotive and beoperated by the engineer or may be of the portable type carried by abrakeman or other train operating personnel. The radio control versionhas the advantage over the hard wire type that it can be applied toindividual cars without requiring modification of the entire train or ofthe service air brake system.

FIG. 7 shows another type of hand brake mechanism and release whichutilizes the brake cylinder 62 already on a railway car. In this versionof the invention the brake cylinder 62 is modified by replacing thestandard piston rod with a form of piston rod 64 which can be latchedinto a locked position with the brakes 66 in applied condition in thiscase the parking brake is applied by normal operation of the service airbrake cylinder 62 and held in applied condition by a latching detent 70controlled by piston rod 68 of the latching cylinder 72. Air pressure ina separate hand brake air pipe 38 controls the operation of latchingcylinder 72. Air pressure in the hand brake air pipe 38 is applied tothe release chamber or upper end 74 of latching cylinder 72 as viewed inFIG. 7 to withdraw latching detent 70 from the piston rod 64 so that thebrakes 66 can be released when pressure in the chamber 78 of the brakecylinder 62 exceeds the pressure in the chamber 80 thereof. A throttlingvalve 76 is interposed between the hand brake air pipe 38 and thelatching cylinder 72 to delay the release of hand brakes. In thisversion of the invention, release of the hand brakes will take placethroughout the train and is under the direct control of the engineer.

FIG. 8 shows a system similar to the system shown in FIG. 7 except thatit avoids the necessity of a separate hand brake air pipe andsubstitutes electrically or electronically operated controls 82 forcontrolling the application of air pressure from the service brake airpipe 20 to operate the latching cylinder 72 to withdraw detent 70 andpermit the hand brakes to be released. The controls 82 are connected byan electrical conductor 54 to a switch or other control 58 operated bythe engineer. Instead of an electrical conductor 54 the controls 82 mayinclude a receiver and associated devices for operation by a signal froma radio or infrared control 60. The radio control 60 can be located inthe locomotive and be operated by the engineer or may be of the portabletype carried and operated by a brakeman or other train operatingpersonnel. The radio control has the advantage that it can be applied toindividual cars without requiring modification of the entire train or ofthe service air brake system. As will be understood by those skilled inthe art, the valve 56 may be operated directly by the switch 58 or bytransmissions from control 60 and the separate control module 82dispensed with.

FIG. 9 shows a hand brake system particularly adapted for use on railwaycars having truck mounted brakes similar to the system previouslydescribed in connection with FIG. 4. The identical numerals are appliedto identical components in FIGS. 4 and 9. The system shown in FIG. 9,however, eliminates the necessity for a separate hand brake air pipe.Air pressure to compress spring 46 in the parking brake cylinder 42 toeffect the release of the hand brakes is supplied from the service brakeair pipe 20 through a choke or motoring valve 39 and a double checkvalve 86. As can be seen, when the service brake air pipe 20 is charged,air pressure is metered through valve 39 and one side 88 of double checkvalve 86 and through pipe 90 to the parking brake release chamber 48.This compresses spring 46, which normally expands the parking brakes 44into a braking position, releasing the parking brake 44. The passage ofair from service brake air pipe 20 to the brake cylinder 42 iscontrolled by brake cylinder control valve 92 which controls airpressure in pipe 84 and pipe 94 to the service brake cylinder. When airpressure in pipe 94 is higher than the brake pressure in pipe 90, whichoccurs in the event of a severe service brake application, air pressurefrom pipe 94 will pass through the other end 96 of double check valve 86into the chamber 48 of parking brake cylinder 42 preventing theapplication of parking brakes 44 until the pressure in the brakecylinder pipe 94 is substantially reduced. This prevents a break-in-twoor other severe brake application from causing both the parking brakesand the service brakes to be applied simultaneously.

FIG. 10 shows a form of the invention in which a conventional hand brakeactuator 28 is used in connection with an automatic hand brake releasesystem which includes a release actuator 98 which is biased into thebrake applying condition by a compression spring 100. The system furtherincludes a linkage 102 connected to the piston rod 104 of piston 106 inthe release actuator. With the hand brakes released the system will bein the condition shown in FIG. 10. The hand brakes are manually appliedby turning the handwheel 29 of hand brake actuator 28 moving the releaseactuator 98 to the right as viewed in FIG. 10. Spring 100 will maintainpiston 106 and piston rod 104 in the position shown effecting brakeapplication through linkage 102. When the service brake air pipe 20 ischarged, air pressure passes from pipe 20 through timing valve 110 intothe chamber 108 of release actuator 98 causing piston 106 to move to theleft as shown in the drawing, compressing spring 100 and causing linkage102 to move in a manner which will effect the release of the brakes 44.Preferably timing valve 110 will not delay the supply of pressurized airto release the hand brakes. The hand brake actuator 28 will remain in acondition in which hand brakes will be applied when the piston 106 ofrelease actuator 98 is allowed to return to the position shown in FIG.10. When service brakes are applied there will be a drop in pressure inpipe 20 but valve 110 will delay the escape of air from chamber 108 andthe hand brake will not be reapplied until train speed is substantiallyreduced. The hand brakes can be manually released at any time throughhand brake actuator 28.

FIG. 11 shows a system which also utilizes a conventional hand brakeactuator 28 of the quick release type which is operated by a solenoid120 which has a link or rod 122 connected to hand brake release lever124. Solenoid 120 is controlled by an electrical or electronic controlsystem 126 which in turn is controlled by an external signal applied inone of the manners described below. The electrical control 126 may beoperated by current sent along electrical conductor 127 through a switch128 controlled from a central location such as the locomotive andoperated by the engineer or other member of the train crew. Control ofsolenoid 120 may be initiated by a radio or infrared signal generated bya transmitter 130 which may be controlled by the engineer from thelocomotive or may be of the portable type operated by another member ofthe train crew. The radio control eliminates the necessity to applywires to the railway train and makes it possible to convert single carsto this system of hand brake release. As another manner of controllingthe operation of solenoid 120, a trackside signal of the active or inerttype may be used. The active type would generate a radio signal when atrain was passing which would be received by the electronic controlsystem 126 and cause the release of the hand brakes. The inert typecould be a resonant coil, not shown, located at trackside which wouldcooperate with circuitry in the electronic control 126 to produce aresonant condition in such circuitry and cause the application ofelectrical power to solenoid 120 to effect release of the hand brake.Alternatively, as shown in FIG. 12, the solenoid 120 may be replaced byan electrically operated valve 121 and the lever 124 operated by aconnecting rod or link 123 operated by a pneumatic cylinder 125. Airpressure to operate the cylinder 125 can be supplied from the servicebrake air pipe 20.

It is within the scope of this invention to use a mechanical linkage ormember, not shown, located at a predetermined point on the track orwayside which will contact the quick release lever of a hand brakeactuator and mechanically release the hand brakes on cars passing thatpoint.

Another form of the invention, shown in FIG. 13, utilizes a separatehand brake air pressure system comprising a hand brake air pipe 38. Theair pressure in pipe 38 is controlled from a central location, such asthe locomotive cab, by a member of the train crew. A quick release handbrake actuator 28 has its release lever 26 connected by linkage 24 to apneumatic release cylinder 22. When the hand brake air pipe 38 ischarged with air, the release cylinder 22 will be activated, operatingthe quick release lever 26 and releasing the hand brakes on each carconnected to the hand brake air pipe 38. An indication that all handbrakes have been released is obtained from the end of train pressuremonitor, not shown, which will indicate the air pressure in the handbrake air pipe 38 at the rear Of the train. When the hand brake air pipepressure is at full charge, there is confirmation that all hand brakeshave been released.

In the form of the invention shown in FIG. 14, the hand brakes will notbe released until and unless the air pressure in the service brake airpipe 20 and the auxiliary reservoir on a railway car reaches apredetermined level of charge indicating that service brakes arereleased and hand brakes can be released. This is accomplished byinserting a hand brake control valve 132, having a valve spool 134, intothe pipe 136, 138 which carries air from the hand brake air pipe 38 tothe release cylinder 22. When air pressure in the auxiliary reservoir140 is below the predetermined level, the spool 134 will be in theposition shown in FIG. 14 and the passage through valve 132 from pipe136 to pipe 138 and the hand brake release cylinder 22 will be closed sothe hand brake cannot be released. At the predetermined level ofpressure, valve spool 134 will move to the left allowing hand brake airpipe air to pass through passage 135 of valve 132 to the releasecylinder 22 which will operate to release the hand brakes. Indicationsthat the hand brake control valves on the train have been operated tothe release position and that the hand brake release cylinders haveoperated are provided by the brake pipe flow indicator, not shown, whichshows air flow from an air compressor, not shown, on the locomotive tothe brake pipe and by the end of train monitor previously referred to.Train personnel are thus advised that the train's hand brakes are incondition to permit movement of the train.

The form of the invention shown in FIG. 15 provides a readily apparentvisual indication that a hand brake is applied. When the hand brakeactuator 28 is manipulated to engage the hand brakes, in addition toputting tension on a chain or cable, not shown, for engaging the brakes,a pulling force is also applied in the direction of the arrow 142 to thechains or cables 144 which are connected to levers 143 which carry flags146 located in housings 148 on each side of a railway car. As the cables144 move in the direction of the arrow 142, the levers and flags willrotate on pivots 150 and out of their housings to a visible position.Tension springs 152 are connected between levers 143 and a fixed pointon the housings 148 to normally maintain the flags 146 in their housedpositions. Pulleys or other elements shown diagrammatically at 145 maybe provided as necessary. A member of the train crew can make a visualinspection of hand brake or parking brake condition of an entire trainfrom either side of the train merely by looking down the side of thetrain. A visible flag 146 will indicate that a hand brake is applied ona given car and a brakeman needs merely to proceed to that car andoperate the hand brake release lever. To further facilitate the releaseof hand brakes in this arrangement there may be added a set of remoterelease levers 154, one on either side of a car and pivoted by a pivot156 to a suitable structure on the car. Each of the remote releaselevers 154 is connected by suitable chains, cables, pulleys and the likeas necessary, indicated by the numerals 158 and 160 to the release lever26 of the hand brake actuator 28.

FIG. 16 shows an arrangement similar to that of FIG. 15 except that theflags 146 are operated by pneumatic cylinders 160 instead of bymechanical linkage. In this version of the invention a bell crank 164,which is part of the parking brake system, is also operatively connectedto a flag operation valve 168 which controls the supply of air pressureto cylinders 160. Piston 174 of valve 168 is normally held by a spring170 in the position shown in FIG. 16 in which it prevents the flow ofair from the service air brake system through pipe 178 to flag operationcylinders 160 and in which pipe 178 is connected to exhaust port 180.When hand brake actuator 28 is operated to apply the brakes, bell crank164 will pivot about pivot 162 pulling on chain or cable 166 to applythe hand brakes. In addition, a pull in the direction of arrow 171 willbe exerted on chain or cable 184 which is connected by linkage orpulleys as necessary to the piston rod 172 of flag operation valve 168moving piston 174 to the right against the bias of spring 170 andproviding a connection between pipe 176 connected to a source of airpressure, for example the service air brake air pipe or the airreservoir 188 of the service air brake system, and pipe 178 connected tothe cylinders 160. Cylinders 160 operate to pivot flags 146 out of theirhousings 148. When the hand brakes are released, spring 170 returns thepiston 174 of flag operation valve 168 to its position shown in FIG. 16connecting pipe 178 to exhaust port 180. The pressure in pneumaticcylinders 160 will exhaust and flags 146 will be returned into theirhousings 148 by springs 152. Flag operation valve 168 is secured to astationary point on a railway car by suitable means 182 which may be abracket or pivot.

FIG. 17 illustrates a form of the invention similar to that in FIG. 15but illustrating another type of linkage between the cable or chain 144and the flag lever 143. Cable or chain 144 is shown as passing overpulleys or guides, illustrated as a pulley 198, to a pivot 200connecting a pair of links 192 of equal length slidably disposed withinan elongated housing 194. Housing 194 has an elongated opening 196 and apair of opposed openings 206, one at each end. Additional cables orchains 202 each have one end passing through one of the openings 206 andattached to one end 204 of the links 192 and their respective other endattached to one of the flag levers 143. When the hand brake is applied,cable 144 will pull upward on pivot 200 in the direction of arrow 193causing links 192 to be pulled through elongated opening 196 in housing194. This will also cause the ends 204 of links 192 to move inwardtoward each other pulling cables 202 through the openings 206 andpivoting flag levers 143 out of their housings. Rollers 190 may beprovided at the ends 204 of the links 192 for smoother operation of thelinkage. Upon release of the hand brakes, tension on cable 144 will berelaxed and springs 152 will pull the flag levers 143 and links 192 backinto the position shown in the drawing.

FIGS. 18 and 19 illustrate another specific form of mechanism which canbe used in the connection between the bell crank or lever 164 and theflag operating levers 143. As best seen in FIG. 19, a pair of chain orrope drums 208 and 219 are rotatably mounted on an axle or spindle 212which is rigidly secured to a suitable mounting 214 on a railway car. Asingle chain or cable 144 connected to the bell crank or lever 164 isconnected to two chains or cables 216 and 218 which are wrapped over thedrums 210 and 208 respectively in opposite directions and attached toone of the levers 143 of the indicator flags 146.

FIG. 20 illustrates a form of the invention similar to that described inconnection with FIG. 16 using double-acting pneumatic cylinders 260 sothat retraction and retention of the flags 146 into their housings isunder positive power from the cylinders 260 rather than solely under theinfluence of springs 152. In this form of the invention flag operationvalve 168 has a double headed piston with piston heads 220 and 222,exhaust ports 180 and 224 and outlet ports 226 and 228 which areconnected to pipes 230 and 178, respectively. Pipe 178 is connected toone side of piston 261 and pipe 230 is connected to the opposite sidesof pistons 261 of cylinders 260. With the hand brakes released as shownin FIG. 20 spring 170 will hold the piston heads 220 and 222 to the leftas viewed in FIG. 20 so that pipe 178 is connected to exhaust throughports 228 and 180 while pipe 230 is connected through port 226 to thepressure in service air brake reservoir 188. This will hold the pistons261 of pneumatic cylinders 260 in the position shown in FIG. 20, holdingflags 146 in their housings. When the hand brakes are applied, tensionon chain or cable 184 will force the piston heads 220 and 222 to theright against the pressure of spring 170 connecting port 226 and pipe230 to exhaust through port 224 and connecting pipe 178 through port 228to air pressure in railway car brake cylinder reservoir 188. This inturn will cause the pistons 261 in pneumatic cylinders 260 to move in adirection which will pivot the flags 146 out of their housingsindicating a hand brake applied condition. When the hand brakes arereleased, the compression spring 170 will return the pistons 220 and 222of valve 168 to the condition shown in FIG. 20, operating the pistons261 of cylinders 260 in a direction which will cause the flags 146 to beretracted into their housings.

Turning now to FIG. 25 there is shown a hand brake release system whichcomprises a spring biased pneumatic cylinder 300 having a piston 302,bias spring 348 and piston rod or plunger 304 which contacts a quickrelease lever 306 of a hand brake actuator, not shown. Pivoting of lever306 in the direction of arrow 308 will effect the release of the handbrake. The system also includes a hand brake release valve 314 having apiston 316 which is connected to and controls a reciprocating valve 318.The valve 314 further has a first chamber 320 connected via a pipe 328,through a check valve 324 and a choke valve 326 in parallel and througha connection 310 to the auxiliary reservoir 311 of the service air brakesystem. Valve 314 also has a second chamber 322 connected via pipe 330through an outlet 312 to the service air brake air pipe 20. Slide valve318 has a first passage 332 which is connected to atmosphere or exhaust,a second passage 334 and a third passage 336. A pipe 342 connectscylinder 300 to slide valve 318 and to exhaust at outlet 346 through achoke valve 344. As shown in FIG. 25, the hand brakes are on and the airbrake system including the air pipe 20 and auxiliary reservoir 311 arebeing charged to the predetermined level and the service brakes are offafter a full service or emergency application. At this time chamber 340of pneumatic cylinder 300 is connected to atmosphere through pipe 342and passage 332 of valve 318 and through choke valve 344 and outlet port346. Therefore, piston 302 is maintained in the position shown by acompression spring 348. The system further includes pressure bulb 338which is connected via pipe 350, passage 334, pipe 351 and outlet 312 tothe service air brake air pipe 20. For an initial period of time duringthe air brake system charge cycle, air pressure in chamber 322 andpressure bulb 338 will exceed the pressure in chamber 320 of releasevalve 314 because the flow of air into chamber 320 is restricted bychoke valve 326. Spring 352 will be compressed and the positions ofpiston 316 and the body of valve 318 will remain as seen in FIG. 25.However, in time, sufficient air will pass through choke valve 326 toraise the pressure in chamber 320 to a point where it will substantiallyequal the pressure in chamber 322 resulting in piston 316 movingdownward as viewed in FIG. 25 under the influence of spring 352connecting pipe 350 to pipe 342 through passage 336. This will cause airin pressure bulb 338 to flow quickly into chamber 340 of cylinder 300,pivoting quick release lever 306 in the direction of arrow 308 andreleasing the hand brakes. Bulb 338 and chamber 340 will also beconnected to exhaust through choke valve 344 and outlet 346 and thepressure in them will eventually dissipate allowing spring 348 to pushpiston 302 back to the position shown in FIG. 25. The hand brakes cannow be manually operated. The system will remain in this condition withpiston 316 of release valve 314 in its downward position and piston 302of cylinder 300 in its upward position until there is another fullservice or emergency application of the service air brakes when therelease valve will go through another cycle. A full service or emergencyapplication of service air brakes will cause both the brake pipe 20 andthe auxiliary reservoir 311 pressure to be reduced. When the servicebrakes are released the service air brake system will begin to rechargewith air. As previously described, the pressure in chamber 322 will risefaster than the pressure in chamber 320 so that piston 316 will beforced into its position illustrated in FIG. 25 and will go through arelease operation cycle as described. This correlates to the air braketest procedure earlier described and ensures that hand brakes or parkingbrakes will be released automatically whenever an air brake test isperformed prior to a train leaving a yard or terminal.

FIGS. 21 through 24 show a modification of the system shown in FIG. 25which modification includes a release ensuring feature. In addition tothe elements described in connection with FIG. 25, this system alsoincludes a release ensuring valve 362 and a brake pressure exhaust valve360. Release ensuring valve 362 is connected by a pipe 366 to theexhaust side of choke valve 344. It has a valve body 370, a spring 372which biases the valve body 370 toward the left as viewed in FIG. 21 andan exhaust port 374. In this position of valve body 370 pipe 366 isconnected to atmosphere through exhaust port 374. Valve body 370 isconnected by a chain or cable 368 to the hand brake mechanism in such amanner that application of the hand brakes will cause valve body 370 tomove to the right and communication between pipe 366 and exhaust port374 will be cut off as can be seen in FIG. 22.

Brake pressure exhaust valve 360 has a piston portion 381 in which thereis a piston head 376, an exhaust portion 365 which has a chamber 379having an exhaust port 378 and a valve head 377 connected to the pistonhead 376 and reciprocable within chamber 379 to control the opening andclosing of exhaust port 378. A pipe 364 connects outlet 312 to chamber379.

As was previously described, after either a full service or emergencyapplication of the service air brakes, air will be supplied to chargethe brake pipe and the auxiliary reservoir, the pressure in chamber 322will rise as the pressure rises in brake pipe 20 while the pressure inchamber 320 will rise more slowly due to the choke valve 326 interposedbetween the auxiliary reservoir and the chamber 320. This will causepiston 316 to move upward against the pressure of spring 352 and assumethe position shown in FIG. 22. Eventually the pressure in chamber 320will approximate the pressure in chamber 322 and piston 316 will movedownward under the influence of spring 352 to the position shown in FIG.23. When this occurs, pressure bulb 338 will send compressed air intochamber 340 of hand brake release cylinder 300 tripping quick releaselever 306 and releasing the hand brakes. Release of the hand brakes willalso relieve tension from chain or cable 368 permitting valve body 370to be moved by spring 372 to the left to its original positionexhausting air from chamber 340 of release cylinder 300 and frompressure bulb 338 through pipes 342 and 366 and pipes 350 and 353respectively. In the event that the hand brakes are not released for anyreason such as, for example, the fracture of release lever 306, and thehand brakes remain applied, tension on chain or cable 368 will remain,holding valve body 370 to the right in the position shown in FIG. 24.This will prevent the escape of air in release cylinder 300 and pressurebulb 338 to atmosphere and the pressure in those areas will pass throughchoke valve 344 into the piston portion 381 and cause the piston 376 ofbrake pressure exhaust valve 360 to move to the right compressing spring380 and opening exhaust port 378. When this occurs pipe 364 will connectthe brake pipe 20 to atmosphere causing application of the servicebrakes so that the train cannot be moved. This ensures that unless allhand brakes are released the train cannot be moved.

As will be understood by those skilled in the art, all or portions ofthe apparatus disclosed in connection with the hand brake or parkingbrake release system may be enclosed in a single package or unit wherebyits installation would require only the necessity of making externalpipe connections from the service air brake air pipe and from theauxiliary reservoir.

FIG. 26 is a block diagram of a hand brake release system of theinvention which will operate automatically as long as it is connected tothe service air brake air pipe 20 even if the service air brakes on aparticular railway car are shut off. It comprises a hand brake releasevalve 400 which controls the supply of air to a hand brake releasecylinder, not shown. The hand brake release valve 400 is itselfcontrolled by a T valve 384 connected to the service brake air pipe 20in parallel with an air brake shut off valve on cutout cock 422. Thehand brake release valve 400 is also connected to the service air brakebrake cylinder 404 and the railway car air brake control valve 92. Valve400 has a main valve slide 408 which is biased by spring 410 toward theposition shown in FIG. 28. Normal operation of the system will bedescribed in connection with FIG. 28, normal operation being consideredthe conditions prevailing when the service air brake shut off valve 422is open or on and the service brakes not applied. As can be seen in FIG.28, inlet port 386 of T valve 384 is connected to air pressure in airbrake pipe 20 by pipe 388. In the normal position described air pipe airpressure is applied to port 386 and also to port 390 of T valve 384.Therefore, spring 392 holds the valve body 394 in the position shown inFIG. 28 connecting port 396 to exhaust. This connects port 402 of handbrake release valve 400 through ports 398 and 396 to exhaust so that thehand brake release cylinder, not shown, does not operate. The handbrakes can be applied manually and will remain on until released asdescribed below. Release valve 400 also includes an equalizing portion403 which has a chamber 405 in which a slide 418 is mounted forreciprocating movement. In one position of slide 418 as seen in FIG. 28,in which valve slide 418 is normally held by a spring 420, a passage 407in the valve slide is out of registry with passage 409 which isconnected to exhaust through chamber 405. In another position of slide418 passages 407 and 409 are in registry and chamber 416 is connected tochamber 412 of release valve 400. When air brakes are applied, pressurein pipe 401 and chamber 416 of release valve 400 will rise and handbrake release valve 400 will assume the position shown in FIG. 29. Airpressure from service air brake brake cylinder 404 in FIG. 26 is appliedto port 406 of hand brake release valve 400 raising the pressure inchamber 416 which moves slide 418 downward as viewed in FIG. 29compressing spring 420, lining up passages 407 and 409 and connectingchamber 416 with chamber 412. Pressure in chamber 416 also causes slide408 to move to the right compressing spring 410 and connecting pressurein chamber 412 through port 402 to the hand brake release cylinder, notshown, to release the hand brakes. In time the pressure in chambers 416and 412 equalizes and spring 410 causes slide 408 to move back to theposition shown in FIG. 28, connecting the hand brake release cylinder toexhaust. The hand brakes can again be applied if desired.

FIG. 27 shows the system of FIG. 26 with the air brake system shut offby means of shut off valve or cut-out cock 422. As will be seen fromFIG. 27, when shut off valve 422 is closed, air pressure will be appliedto the lower end of T valve 384 through port 386 but there will be noair pressure through pipe 426 and port 390 to the top of valve slide394. Spring 392 will remain compressed and air pressure will be suppliedthrough passage 428 and port 396 of T valve 384 to ports 398 and 402 ofhand brake release valve 400 with slide 408 in the position shown. Therelease cylinder will operate, releasing the hand brake and the handbrake cannot be operated until air in the service air brake pipe 20 isexhausted. When this occurs there will be no pressure at inlet port 386of the T valve, spring 392 will force valve slide 394 down and intoexhaust position seen in FIG. 28, releasing pressure from the hand brakerelease cylinder and allowing the hand brake to be operated.

FIG. 30-32 illustrates a hand brake release system designed to releasehand brakes or parking brakes automatically upon completion of an airbrake test when a train is preparing to leave a yard or a terminal.

As seen in FIG. 30, there is provided a hand brake release valve 440having a release portion 443 and a valve stop portion 445. Releaseportion 443 has a first chamber 441 and a second chamber 442. Chamber441 is connected to the air brake air pipe 20 of the service air brakesystem on the train and chamber 442 is also connected to such air pipethrough a valve slide 444. When valve slide 444 is in the position shownin FIG. 30, passage 446 in the valve slide will be in registry withpassage 448 and provide a connection from chamber 442 to the service airbrake pipe 20. Valve slide 444 is provided with a slot or detent 450which is engageable by the stem 452 of a valve stop piston 454 mountedfor reciprocal movement in a chamber 456 in the valve stop portion 445.Valve slide 444 is normally urged toward its lowermost position as shownin FIG. 30 by spring 458. A valve slide 460 is mounted for reciprocatingmovement in chamber 442 and is normally urged toward the left of valvechamber 442 by spring 462 as viewed in FIG. 30. Passage 464 connectspassage 448 and consequently valve chamber 442 to valve chamber 441through a restriction or choke 466. Port 468 is an exhaust port open toatmosphere and outlet port 470 is connected by a pipe 472 to a handbrake release cylinder (not shown). Valve stop portion 445 has a port478 which is connected to the service brake air pipe. A restrictedopening or choke 474 is provided through the piston 476 of valve stoppiston 454. Operation of the hand brake release system shown in FIG. 30is as follows. When there is no pressure in the system, as when a trainis first made up, the valve slides 444 and 460 will be in the positionshown in FIG. 30 and valve stop piston 454 will be free to move in valveslide chamber 456 and may assume a position toward the right end ofvalve slide chamber 456 with its stem 452 out of engagement with theslot in valve slide 444. With the first charging of the service airbrake air pipe 20 pressure applied to valve stop piston 454 through port478 will cause the valve stop to move to the left causing its stem 452to be engaged in the detent 450 of valve slide 444. This will preventmovement of valve slide 444. Both the first chamber 441 and the secondchamber 442 will remain connected to the service air brake air pipe andthe hand brake release cylinder will remain connected to exhaust throughports 468 and 470. When the first brake application is made in thecourse of an air brake test, pressure on the right side of the valvestop 454 is reduced while pressure on the left side remains initiallyhigher since air from chamber 456 can only be exhausted through choke474. This causes valve stop 454 to move to the right freeing valve slide444 which is moved upward as shown in FIG. 31 compressing spring 458 aspressure in the service air brake air pipe continues to rise. This movespassage 446 out of registry with passage 448. Valve slide 460 remains tothe left, as viewed in FIG. 31, under the influence of spring 462. Whenthe service air brake system is charged, spring 460 will initiallyremain in the position shown under the influence of spring 462 since airpressure on both sides of valve slide 460 is the same.

When a full service brake application is made in the course of an airbrake terminal test, pressure in chamber 441 is also reduced but priorto a reduction in the pressure in chamber 442 by virtue of the presenceof choke 466. Slide 460 remains in the position shown in FIG. 31 underthe influence of spring 462. After the air brakes are released,following the full application of air brakes in the course of the airbrake test, pressure in the air brake air pipe will rise as the systemis charged. Pressure will rise first in chamber 441 since air fed intothe cheer 442 must pass through the restriction imposed by choke 466.Therefore, slide 460 will move to the right compressing spring 462 asshown in FIG. 32. Pipe 472 which connects the hand brake releasecylinder to chamber 441 will be provided with compressed air and willeffect release of the hand brakes. In due course air pressure in chamber442 will equalize with air pressure in chamber 441 as air is admittedthrough choke 466 to cheer 442 and spring 462 will return valve spring460 to the position in which it is shown in FIG. 31. The hand brakerelease cylinder will again be connected to exhaust and the hand brakesmay be manually operated.

FIGS. 33, 34 and 35 illustrate a hand brake release control valve whichcan be used in conjunction with a hand brake release system toselectively determine whether or not the automatic hand brake releasewill operate. The valve 500 may be a ball valve with a body 501 havingan inlet port 502, an outlet port 504, an exhaust port 506 and a ball508 mounted for rotation within body 501. The ball 508 has a primary orfirst passage 510 of a predetermined diameter extending through thecenter of the ball and a secondary or second passage 512 extendingthrough a segment 514 of the ball lying on one side of a longitudinalcenterline of the first passage 510. Second passage 512 is of smallerdiameter than the diameter of the primary passage. Inlet port 502 is inaxial alignment with outlet port 504 and has substantially the samediameter as port 504 and passage 510 so that when the valve is in itsopen or normal position as shown in FIG. 33, passage 510, inlet port 502and outlet port 504 form a continuous substantially unobstructed passageof a predetermined diameter through the valve body 501. Inlet port 502is connected to the air brake air pipe 20 and outlet port 504 isconnected to the hand brake release system of the invention. Exhaustport 506 is located 90° from each of the inlet and outlet ports andpassage 512 is angled at its ends 516 and 518 so that when ball 508 isin the position shown in FIG. 34 outlet port 504 will be connected toexhaust port 506 through passage 512.

FIG. 34 shows the control valve in its exhaust position in which all airin the hand brake release system is exhausted to atmosphere. Whenreleased, the control valve will automatically return under springpressure to the open or normal position making the release system againoperative.

FIG. 35 shows the valve in its closed position. In this position thehand brake release valve is cut off from air pressure in the service airbrake air pipe 20 and the automatic hand brake release will beinoperative until the control valve is manually returned to the openposition.

Although certain preferred embodiments of the invention have been shownand described, it should be understood that many changes andmodifications may be made therein without departing from the spirit andscope of the appended claims.

We claim:
 1. A railway parking brake release system for a railway train having at least one car equipped with fluid pressure operated service brakes and an auxiliary parking brake apparatus and having a first mechanism for actuating such auxiliary parking brake apparatus to a braking condition and a second mechanism for releasing such auxiliary parking brake apparatus, said release system comprising:(a) an inlet connectable to a source of fluid pressure for such service brakes; (b) a fluid pressure responsive valve means in communication with said inlet and responsive to predetermined levels of fluid pressure therein to be conditioned to one of an operative condition and an inoperative condition; (c) a fluid pressure operated cylinder having a reciprocally operated piston controlled by said valve means and operable from a first position when said valve means is in an inoperable condition, in which such auxiliary parking brake apparatus may be actuated to a braking position, to a second position when said valve means is in an operative condition in which said auxiliary parking brake apparatus will be released upon operation of said cylinder; and (d) a pressure bulb connected to said fluid pressure operated valve when said piston is in said second position.
 2. A parking brake release system, according to claim 1, in which said fluid pressure operated valve is adapted to interconnect said pressure bulb to said inlet as necessary to charge fluid pressure into said pressure bulb, and thereafter interconnected to said fluid operated cylinder so that fluid pressure within said pressure bulb will cause such release of such auxiliary parking brake release.
 3. A parking brake release system, according to claim 2, wherein said parking brake release system further includes a choke valve disposed on a conduit interconnecting said fluid operated cylinder with said fluid operated valve adapted to permit delayed venting of said fluid operated cylinder to atmosphere.
 4. A parking brake release system, according to claim 3, wherein said parking brake release system further includes a pressure release insuring means for insuring release of pressure from said fluid pressure operated cylinder when said valve means is in said inoperative condition.
 5. A parking brake release system, according to claim 4, in which said pressure release insuring means is a release valve operable by such mechanism for actuating such auxiliary parking brake.
 6. A parking brake release system, according to claim 5, wherein said parking brake release system further includes a brake pressure exhaust valve adapted to permit retarded release of fluid pressure from said pressure operated cylinder.
 7. A railway parking brake release system, for a railway train having at least one car equipped with fluid pressure operated service brakes, a source of fluid pressure for operating such service brake, and an auxiliary parking brake apparatus having a first mechanism for actuating such auxiliary parking brake apparatus to a braking condition and a second mechanism for releasing such auxiliary parking brake apparatus, said release system comprising:(a) an inlet connectable to such source of fluid pressure for operating such service brakes; (b) a fluid pressure operated cylinder having a fluid operated reciprocal piston adjustable between a first position incapable of releasing such auxiliary parking brake and a second position as will release such auxiliary parking brake; (c) a fluid pressure responsive valve means in communication with said inlet and adapted to operate said fluid pressure operated cylinder, responsive to fluid pressure at said inlet, such that said fluid pressure operated cylinder can be positioned to release such auxiliary parking brake only when fluid pressure at such inlet is adequate to operate such service brakes; and (d) a pressure bulb connected to said fluid pressure operated valve when said piston is in said second position.
 8. A parking brake release system, according to claim 7, in which said fluid pressure operated valve is adapted to interconnect said pressure bulb to said inlet as necessary to charge fluid pressure into said pressure bulb, and thereafter interconnected to said fluid operated cylinder so that fluid pressure within said pressure bulb will cause such release of such auxiliary parking brake release.
 9. A parking brake release system, according to claim 8, in which said fluid pressure operated valve is adjustable between a first position which will permit fluid pressure from said inlet to be charged into said pressure bulb while venting said pressure operated cylinder as necessary to maintain such auxiliary parking brake applied, and a second position which will interconnect said pressure bulb with said pressure operated cylinder as necessary to permit such auxiliary parking brake to be released.
 10. A parking brake release system, according to claim 9, in which said fluid pressure operated valve is in part operated in response to fluid pressure at said inlet, and in part operated in response to fluid pressure in an auxiliary pressure reservoir which is charged with fluid pressure in proportion with said fluid pressure at said inlet.
 11. A parking brake release system, according to claim 10, wherein said parking brake release system further includes a check valve interconnected with a choke valve disposed on a conduit between said fluid pressure operated valve and said auxiliary pressure reservoir. 